Dekker J H1, Visser E1, Vermeulen K M2, Messelink E J3, Schram A J4, Kollen B J1, Berger M Y1, de Bock G H2
1. Department of General Practice, University Medical Center Groningen, Groningen, The Netherlands, 2. Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands, 3. Department of Urology, University Medical Center Groningen, Groningen, The Netherlands, 4. Department of Gynaecology, University Medical Center Groningen, Groningen, The Netherlands